Fuel injection pump



April 11, 1950 F. A. THAHELD FUEL INJECTION Pun? Filed Feb. 11, 194eIII' Hllbl FIG FIG. 4

FRED H. 'THQHELp (lwucno'b mit# QW M FIQ. l

FIG.

ali/fm FIG.

Patented Apr. ll, 1950 l FUEL INJECTION PUMP Fred .A. Thaheld, Brea,Calif., assignor, by mesne assignments, to Diesel Power Inc.,Pittsburgh, Pa., a corporation of Pennsylvania Application February 11,1946, Serial No. 646,852

7 Claims. (Cl. 10S-228) l This invention relates to internal combustionengines and is particularly directed to an improvement in the fuelinjection system of the type commonly employed in connection withengines of the Diesel type.

Fuel injection pumps of a conventional de.

sign are customarily provided with means for varying or controlling theamount of fuel injected into each cylinder for each stroke of thepiston. By this means the speed of the engine and the power availableare normally controlled. I have found that this conventional controlmeans for the fuel injection pump is not entirely satisfactory when theengine is being started initially. During the cranking operation for thepurpose of starting the engine the control lever for the fuel. injectionmechanism must be set to deliver a larger quantity of fuel than normallywould 'be injected during normal operation of the engine. When the fuelcharge ignites during starting operations, the rotation of the crankshaft is accelerated very rapidly with the result that the engineoperates at excessive speed for an interval of the time before thecontrol mechanism can be readjusted to cut down the quantity of fueldelivered.

It is accordingly the principle object of my invention to provide animproved fuel injection mechanism which automatically will preventracing of the engine immediately after starting.

Another object of this invention is to provide an improved fuelinjection system which acts as an automatic governor when the engine isidling and thereby prevents undesirable uctuations in idling speed.

Other objects and advantages will appear hereinafter.

In the drawings:

Fig. 1 is a sectional end elevational showing a conventional form offuel injection valve, but which employs a fuel delivery valve embodyingmy invention.

Fig. 2 is a perspective sectional elevation on an enlarged scale showingdetails of the device shown in Fig. 1.

Fig. 3 is a sectional elevation of the portion of the device shown inFig. 2 with the fuel delivery valve illustrated in closed position.

Fig. 4 is a view similar to Fig. 3 but with the fuel delivery valveillustrated in open or discharging position.

Flg. 5 is a side elevation of the fuel delivery valve.

Fig. 6 is a bottom end view of the valve shown in Fig. 5.

Referring to the drawings, the f-uel injectionpump to which my inventionis applicable may include a drive shaft I0 having a series of cam lobesIl formed thereon, one for each individual pump. The cam Ylobes eachdrive a follower roller I2, which is rotatably Supported within a crosshead I3. The cross head |3 is slidably mounted within a bore I4 in thehousing I5. A fitting I6 threadedly connected to the cross head I3carries a spherical seat I1 which is engaged by a spherical end I8 onthe lower end of the plunger I9. A compression spring 20 encircles theplunger |9 and is adapted to maintain Ythe spherical surfaces I1 and I8in contact as well as to prevent separation of the cam |I and thefollower roller I2. g

Mounted within the pump housing I5 for pivotal movement about the axisof the plunger I9 is a sleeve 2|. Fixed to the housingA and projectingdownwardly within the sleeve 2| is a barrel 22y provided near its upperend with an inlet port 23' and an outlet port 24. The plunger I9 isground and lapped to t the bore of the barrel 22 and at its upper endthe plunger is provided with an axially extending slot 25, one side ofwhich is determined by a helical surface 26. The plunger I9 reciprocateswithin the barrel 22 with a constant length stroke determined by theshape of the cam Means are provided for turning the plunger within thebarrel 22 and, as shown, this means includes a laterally projecting foot21 on the plunger which reciprocates in slots 28 formed on the lower endof the sleeve 2|. The upper end of the sleeve 2| carries a gear segment29 which meshes with rack teeth 30 formed on the reciprocable controlbar 3|. Longitudinal movement of the control bar 3| serves to rotate thesleeve 2| and hence turn the plunger I9 within the barrel 22 by means ofthe foot 21 and slot 28.

Fixed to the upper end of the barrel 22 and in coaxial relationtherewith is a delivery valve f1tting 32 having a central cylindricalbore 33 terminating at its upper end in a valve seat 34. The deliveryvalve fitting 32 is maintained in place by an enclosure fitting 35 whichis threaded within the housing I5. The enclosure fitting 35 has acentral chamber 36 enclosing a coil spring 31 which acts against theupper face of a fuel delivery valve 38. The fuel delivery valve 38 has aconical sealing surface 39 adapted to seat on the valve seat 34. Axiallyspaced from the conical sealing surface 39 is a cylindrical piston 40which ts within the bore 33 in slidable relation. A plurality of guidevanes or flutes 4| is provided on the lower end of the delivery valve38. These utes 3 extend radially outwardly and are shaped to nt insliding contact with the cylindrical bore 33.

The mechanism described so far is conventional in character and operatesin the following manner:

Rotation of the cam II causes reciprocation of the cross head I3 andplunger I9. When the upper end of the plunger passes the position shownin Fig. 2 and moves upwardly past the inlet port 23, a quantity of fuelis trapped within the upper end of the barrel 22 above the plunger Il.Upward movement of the plunger raises the pressure of the fluid sotrapped and this pressure acts on the fuel delivery valve 38 to move itin an upward direction in opposition to the compression spring 31. Whenthe piston 40 moves out of the bore 33 fuel may pass upwardly betweenthe flutes 4I and past the valve seat 34 into the chamber 36. Adischarge line (not shown) is connected to the upper end of the fitting35 for conveying injected fuel to the engine cylinder by way of thecustomary nozzle valve in the other.

end of the discharge tubing. Upward movement of the plunger I9 causesdischarge, of fuel past the fuel delivery valve 38 in proportion tomovement of the plunger I9 until the helix surface 26 registers with theoutlet port 24. At the instance of registry the pressure of the fuelWithin the bore 33 and within the barrel above the plunger is ventedthrough the slot 25 and the space below the helix 26 to the outlet port24. The resulting drop in pressure within the bore 33 causes the coilspring 31 to move the fuel delivery valve 33 quickly to closed position.At the time of closing, the piston 40 reenters the bore 33 and hencereduces the pressure within the chamber 36 and discharge tubing (notshown) by an amount proportional to the volume of the piston 40. Thispressure reduction in the discharge tubing immediately followinginjection of fuel is beneficial since it permits the nozzle valve at theother end of the discharge tubing to snap shut on its seat, thusinstantaneously terminating the injection of fuel.

The fuel delivery valve 33 does not reopen until l the plunger I9 isagain raised during the regular stroke of the pump. Variations inquantity of fuel delivered are effected by turning the plunger I9 in themanner described above. Turning of the plunger I9 within the barrelserves to change the i point at which the helix 26 registers with theoutlet 'port 24 during the stroke of the plunger I3. It, therefore, willbe understood that while the plunger stroke does not vary, the quantityof fuel delivered per stroke can be changed at will by turning theplunger I9 within the barrel 22 by means of the control bar 3|.

The improvement to which this invention is directed comprises theprovision of a by-pass or supplementary passage in the fuel deliveryvalve 38 which communicates with the bore 33 above and below the piston40. As shown in the drawings, this by-pass includes an axial hole 42drilled centrally from the lower end of the valve along the axis thereofto a, position adjacent the sealing surface 39. A lateral port 43 isthen drilled into the central hole 42. The size of the hole 42 and theport 43 is important since it controls the amount of fuel which willpass through it when the valve surface 39 is unseated. From actualperformance data I have found that the addition of this supplementarypassage 42, 43 materially facilitates easy starting of the engine. Underthe relatively slow cranking speed, the delivery valve 36 reciprocatesin the bore 33 at a correspondingly slow speed since the cam shaft ID ofthe fuel injection pump is driven in timed relation with the enginecrank shaft. During this relatively slow movement, the supplementarypassage 42. 43 acts to deliver an increased quantity of fuel for eachstroke of the engine piston. When the fuel charge ignites and the enginebegins to run on its own power, the engine crank shaft is acceleratedvery rapidly, so that only a few revolutions are required to bring theengine crank shaft up to operating speed. The rapid increase in speed ofthe engine crank shaft is reflected in a rapid increase in rate ofreciprocation of the plunger I9 and hence of the delivery valve 38.Under normal speed or high speed operation, the effect of thesupplementary passage 42, 43 becomes negligible since the time requiredto pass any appreciable fluid through the passage 42, 43 becomes shorterand shorter as the speed of the engine increases.

The supplementary passage 42, 43 has an additional beneficial effect onthe engine operation since it acts as an automatic governor to insureinjection of adequate quantities of fuel to maintain the idling speed ofthe engine sufficiently high for reliable operation without possibilityof stopping. Thus, when the engine speed tends to fall below a safevalue, the effect of the supplementary passage 42, 43 is to supplyadditional quantities of fuel and hence, increase the engine speed tothe minimum permissible value for safe idling. Should the engine speedexceed the desired idling speed, the effect of the supplementary passage42, 43 decreases with increasing speed with the result that decreasedquantities of fuel are injected and hence the engine speed falls off.Under normal operation of the engine at medium speed and high speed. theeffect of the supplementary passage 42, d3 is negligible.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth, but my inventionis of the full scope of the appended claims.

I claim:

1. In a fuel injection pump for an internal combustion engine, thecombination of a barrel having a reciprocable plunger therein, inlet andoutlet ports communicating with said barrel, a bore adjacent said barrelhaving a valve seat at the outer end thereof, a fuel delivery valveslidably mounted within said bore and havl:.g a sealing surface adaptedto engage said valve seat, an annular piston on said valve axiallyspaced from said sealing surface and adapted to form a sliding fitwithin said bore, the valve having primary passage means whereby fluidin said bore may pass through the valve seat upon movement of the pistonout of the bore, and secondary passage means in said valve terminatingin a lateral port positioned between said piston and said sealingsurface and communicating with the interior of said bore.

2. In a fuel injection pump for an internal combustion engine, thecombination of a barrel having a reciprocable plunger therein, inlet andoutlet ports communicating with said barrel, a cylindrical bore adjacentsaid barrel having a conical valve seat at the outer end thereof, a fueldelivery valve having guide vanes slidably mounted within said bore andhaving a conical sealing surface adapted to engage the valve seat, anannular piston on said valve axially spaced from said conical sealingsurface and adapted to form a sliding nt within said cylindrical bore.

3. A delivery valve for a fuel injection pump having in combination aconical sealing surface near the upper end thereof, an annular pistonaxially spaced from said conical sealing surface defining a cylindricalsurface, a plurality of guide vanes extending radially outwardly andhaving their outer edges shaped to conform substantially to saidcylindrical surface, the guide vanes defining primary passage meanstherebetween terminating at said piston, and secondary passage means insaid valve including an axial passageway extending from the lower end ofthe valve to a point above the position of said annular piston, and alateral port between the annular piston and the conical sealing surfacecommunicating with the axial passageway.

4. A delivery valve for a fuel injection pump having in combination asealing surface near the upper end thereof, an annular piston axiallyspaced below said sealing surface defining a cylindrical surface, aplurality of guide vanes below said piston extending radially outwardlyand having their outer edges shaped to conform substantially to saidcylindrical surface, the guide vanes defining primary passage meanstherebetween terminating at said piston,I and secondary passage means insaid valve extending from a point below said annular piston to a lateraloutlet port between the annular piston and the sealing surface.

5. In a fuel injection pump for an internal combustion engine, thecombination of a cylindrical bore having a valve seat at the upper endthereof, a fuel delivery valve having guide vanes extending radiallyoutwardly into sliding contact with said cylindrical bore, the guidevanes defining fuel delivery passage means therebetween, a conicalsealing surface on said valve axially spaced above said guide vanes andadapted to engage said`valve seat, an annular piston on said valvepositioned intermediate the guide vanes and the conical sealing surfaceand adapted to form a sliding lit within said cylindrical bore,

and fuel bypass means in said valve including a passageway communicatingwith the interior of said cylindrical bore at spaced points above andbelow said annular piston.

6. In a fuel injection pump for an internal combustion engine, thecombination of a cylindrical bore having a valve seat at the upper endthereof, a fuel delivery valve having guide vanes extending radiallyoutwardly into sliding contact with said cylindrical bore, the guidevanes defining fuel delivery passage means therebetween, a conicalsealing surface on said valve axially spaced above said guide vanes andadapted to engage said valve. seat, an annular piston on said valvepositioned intermediate the guide vanes and the conical sealing surfaceand adapted to form a sliding iit within said cylindrical bore,

and fuel bypass means in said valve including an axial passagewayextending from the lower end of the valve to a point above the positionof said annular piston, and a lateralv port between the annular pistonand the conical sealing surface communicating with the axial passageway.

7. In a fuel injection pump for an internal combustion engine, thecombination of a, member provided with a cylindrical bore, saidvmemberhaving a valve seat at one end of the bore, a fuel delivery valveslidably Amounted within said boreand provided with a valve head adaptedto close against said valve seat, the valve having a cylindrical portionadapted to form a sliding seal within said bore, means on the valveforming a relatively large primary passage means whereby fluid in saidbore may pass through the valve seat upon movement of said cylindricalportion out of the bore, and a relatively small secondary passage meansin said valve terminating in a lateral port positioned between saidvalve head and said cylindrical portion and communieating with theinterior of said bore.

FRED A. THAHELD.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS

